Integrated KBE Approach for Design and Analysis of...

MSC Software Confidential MSC Software Confidential

INTEGRATED KBE APPROACH FOR

DESIGN AND ANALYSIS OF GEARS 2013 Regional User Conference

Presented By: Sachin Kulkarni

May 14, 2013

MSC Software Confidential

• Gears are widely used to transmit power and rotary motion with

or without change of speed or direction.

• Many industries such as automotive, aerospace, ship uses spur

and helical gears.

• Traditionally, gears are designed using popular AGMA standards

followed by CAD modelling and manufacturing.

• Recently, FEA is also used to analyse, optimize and validate gear

designs.

• In spite of number of investigations devoted to gear research and

analysis, there still remains to be developed a general integrated

tool for quick and reliable design and analysis of gears.

Background

2


Need for KBE Approach

3

• Currently, gear design and analysis steps (AGMA, CAD, and FEA)

are done independently and are loosely coupled. This uncoupled

traditional process requires 150-200 man-hours in 3-4 calendar

weeks to complete new optimized design of any gear.

• But there is growing need for quicker and optimized designs in

short period of time.

• Hence, the present work aims

– To develop an integrated tool using VB.Net to tightly couple AGMA, CAD

and FEA

– AGMA calculations are automated

– CAD model uses parametric and KBE approach

– FE analysis using Patran and Nastran is automated using KBE approach

– Automatic Report Generation for Design and Analysis

MSC Software Confidential 4

Integrated Gear Designer Tool

• Infosys develops Gear Designer tool to provide end to end

solution. This tool is tight integration of AGMA, CAD and FEA.

• This integrated tool uses Knowledge-Based Engineering (KBE)

approach to embed AGMA rules in calculations and parametric

modelling in CAD/CAE modelling.

• CATIAV5R21 automation is carried out to produce 3D CAD

models of spur and helical gears based on AGMA calculations

embedded into the tool.

• Detailed CAD model is imported in Patran 2010 to carryout FE

analysis using MSC.Nastran 2008 SOL600. Patran Command

Language (PCL) is used to automize Patran.

• Finally, tool also generates complete design and analysis report

in company templates.

• Using this integrated tool, gear design solutions are quick and

standardized. To use this tool user need not to be expert of

CATIA or Patran/Nastran


Gear Designer - Process Flow

5


Gear Designer - User Interface

6

• Following is list of input parameters required

under different tabs to run the tool Gear Type

Transmitted Power

Tooth System

Width to Module Ratio

Pressure Angle

Gear Ratio

Gear Material

Quality of Gears

Number of Tooth on Pinion

Pinion Material

Reliability

Service factor

Life

Others


• Using AGMA procedure safe module is calculated by tool. This module is used to

produce CAD models in CATIA.

• According to AGMA gear tooth failure is avoided by considering the beam

strength and the wear strength.

Gear Designer - AGMA calculations

7


• Once module is known tooth dimensions are calculated.

• Parametric modeling uses parameters to control the dimensions and shape of

CAD model.

Gear Designer – CAD Modeling

8

Quantity Desired Formula

Pitch Diameter D = m.N

Circular Pitch p = .m

Root Diameter Dr = D – d – c

Dedendum Diameter Dd = D – d

Addendum Diameter Da = D + a

Tooth Thickness t = p/2

Clearance c = d = a

2

p


Gear Designer - Sample Inputs for Spur Gear

9

Parameter User Input Parameter User Input

Power to be

Transmitted (KW)

20 Pressure Angle(Deg) 20

No. of Pinion Teeth 18 Helix Angle(Deg) 0

RPM of Pinion 700 Reduction Ratio 2

Quality of Gear 3 Width Ratio 5

Load Characteristics Uniform Tooth Systems Full Depth

Gear Units Condition Open

Gearing

Gear Adjustment At Assembly

Pinion Core

Harness(HB)

300 Gear Core

Hardness(HB)

300

Pinion Surface

Hardness(HB)

300 Gear Surface

Hardness(HB)

300

Pinion Teeth Type Uncrowned Pinion Material Steel - Through

Hardened Grade 1

Gear Teeth Type Uncrowned Gear Material Steel - Through

Hardened Grade 1

Reliability 0.9999 Life(Cycles) 10000000

Span 1000 Service Factor 1.5


CAD Model of Spur Gear

10


FE Model of Spur Gear

11

• Patran-PCL scripts are integrated in tool to

perform meshing using HEX elements. HEX

elements are generated by sweeping QUAD

elements along face width of the tooth.

• Load is calculated using equation below:

• Appropriate tooth contacts are defined to

perform FE analysis using Nastran

• Gears fixed at shaft holes

• SOL 600 is used


Stress Plot of Spur Gear

12

• From FE results contact stress 380 MPa and bending stress is 30 MPa. These

results are very close to AGMA results i.e. bending stress is 29.34 MPa and

contact stress is 382.83 MPa.


• Outcome: Successfully developed integrated tool using KBE

approach for design and analysis of gears. Use of this tool

results in saving of around 100 man-hour per gear design

• Tool Validation: Results of integrated tool are satisfactory and FE

results compares reasonably close to AGMA calculations

validating accuracy and usability of tool.

• Other Benefits:

– The tool also helps in reducing turn-around time as it is completely

automated process eliminating manual operations.

– This tool provides sophisticated functionality and easy user interface

making it easy for infrequent or non-expert users.

Conclusions

13

MSC Software Confidential 14

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